Chapter 28 The Reproductive System

Chapter 28

The Reproductive System

Introduction to the Reproductive System

Objective:

-Specify the principal components of the human reproductive system & summarize their functions.

Reproductive System

The

reproductive system

is the only system that is not essential to the life of the individual

It ensures the continued existence of human beings:

-by producing, storing, nourishing, and transporting functional male and female reproductive cells, or

gametes

Components of the Reproductive System

Gonads:

the reproductive organs that produce gametes and hormones

Ducts that receive and transport gametes

Accessory glands & organs that secrete fluids into the ducts

Perineal

structures, known an

external genitalia

Male Components

Testes:

male gonads

Secrete sex hormones such as testosterone

Produce male gametes, called

spermatozoa

(1/2 billion each day)

During

emission

, mature sperm mix with secretions to form a mixture called

semen

Semen is expelled during

ejaculation

Female Components

Ovaries: female gonads

Release one immature gamete (

oocyte

), per month

Oocyte travels along

uterine tubes

, which end in a muscular organ known as the

uterus

Fertilization

Oocyte matures into an ovum

Ejaculation

introduces semen into the vagina during

sexual intercourse

If fertilization occurs, the uterus will enclose and support a developing

embryo

as it grows into a

fetus

The Reproductive System of the Male

Objectives:

Describe the components of the male reproductive system

Outline the processes of meiosis & spermatogenesis in the testes

Explain the roles played by the male reproductive tract in the handling of spermatozoa

The Testes

Shape of a flattened egg

Hangs within the

scrotum

: a fleshy pouch suspended posterior to the base of the penis

The Testes

Ureter

Rectum

Seminal

vesicle

Prostate

gland

Ejaculatory duct

Bulbourethral gland

Anus

Urinary

bladder

Pubic

symphysis

Spongy urethra

Penis

Ductus deferens

Epididymis

Testis

Scrotum

External urethral

orifice

Descent of the testes

During development of fetus, testes develop inside the body cavity, adjacent to kidneys

Position of testes changes as body enlarges

Testes gradually move inferiorly and

anteriorly

toward anterior abdominal wall

Descent of the testes

is the process of the testes moving through the abdominal musculature

Descent of the Testes

Epididymis

(b)

Diaphragmatic

ligament

Developing

kidneys

Gubernaculum

testis

Mesonephric

duct

Kidney

Testis

Epididymis

Testis

Urinary

bladder

Ureter

Vas

deferens

Epididymis

Testis

Gubernaculum

testis

Superficial

inguinal ring

Testicular

artery and

vein

Testicular

artery and

vein

Gonads

Scrotal cavity

(opened) lined by

tunica vaginalis

2 months

3 months

4 months

7 months

Diaphragmatic

ligament

Urinary

bladder

Scrotum

(opened)

Ureter

Birth

Spermatic

cord

Descent of the Testes

Cryptorchidism

is a condition where one or both of the testes have not descended into the scrotum b the time of birth

They are lodged in the abdominal cavity or within the inguinal canal

The person may become infertile or

sterile

The Spermatic Cords

These are layers of fascia and muscle enclosing the

ductus

deferens and the blood vessels, nerves, and lymphatic vessels that supply the testes

The Scrotum and the Position of the Testes

Testicular artery

Testicular vein

Inguinal

ligament

Superficial

inguinal ring

Scrotal septum

Cremaster muscle

Dartos muscle

Superficial scrotal

fascia

Raphe

Scrotal skin (cut)

Testis (covered by

Visceral layer of

tunica vaginalis)

Epididymis

Pampiniform plexus

Ductus deferens

Deferential artery

Genitofemoral nerve

Testicular artery

Spermatic cord

Inguinal

canal

Urinary

bladder

Penis

Parietal layer of tunica

vaginalis (inner lining

of cremaster muscle,

facing scrotal cavity)

Scrotal cavity

The Scrotum

The scrotum is divided into two

scrotal cavities

, marked by a raised thickening in the scrotal surface known as the

raphe

It consists of a thin layer of skin and underlying superficial fascia

Layers of the smooth & skeletal muscle results in the wrinkling of the scrotal surface

Moves the scrotum to or from the body to provide the desired temperature for sperm production (two degrees Fahrenheit)

Spermatogenesis

Three processes:

Mitosis: 2 daughter cells produced: one is turned into a

spermatocyte

(cell that begins meiosis)

Meiosis: produces

spermatids

(undifferentiated male gametes)

Spermiogenesis

: spermatids differentiate into mature spermatozoa

Spermatogenesis

Tetrad

Synapsis and

tetrad formation

MITOSIS of

spermatogonium (diploid)

MEIOSIS I

MEIOSIS II

Secondary spermatocytes

Spermatids (haploid)

SPERMIOGENESIS(physical maturation)

Spermatozoa (haploid)

Primary spermatocyte

Primary spermatocyte (diploid)

DNA replication

SPERMATOGENESIS

Sustentacular Cells

Play a key role in spermatogenesis

Maintenance of the blood-testes barrier

Support of Mitosis and Meiosis

Support of Spermiogenesis

Secretion of Inhibin

Secretion of Androgen-Binding Protein

Secretion of

Mullerion

-Inhibiting Factor

Anatomy of Spermatozoon

Three Distinct Regions:

Head

: flattened ellipse containing a nucleus with densely packed chromosomes

Middle piece

: contains mitochondria to provide energy to move tail

Tail

: the flagellum that beats in a corkscrew motion to propel sperm

Anatomy of Spermatazoon

(a)

Mitochondria

Spermatid

(week 1)

Spermatozoon

(week 5)

Golgi

apparatus

Acrosomal

vesicle

Nucleus

Acrosomal

cap

Nucleus

Acrosomal

cap

Tail (55





m)

Middle piece

(5





m)

Neck (1





m)

Head (5





m)

Mitochondrial

spiral

Centrioles

Nucleus

Acrosomal cap

Shed

cytoplasm

Fibrous sheath

of flagellum

The Male Reproductive Tract

The

Epidymis

: start of the male reproductive tract

Three Functions:

Monitors and adjusts composition of fluid produced by seminiferous tubes

Acts as a recycling center for damaged sperm

Stores and protects spermatozoa and facilitates their functional

maturization

Male Reproductive Tract

Ductus Deferens

: passageway that carries spermatozoa from epidymis to the

ejaculatory duct

, which empties into the urethra

Urethra: passageway for urinary and reproductive system to the outside environment

Male Reproductive Tract

LM X 1304

(a)

(b)

Body of

epididymis

Ductus

deferens

Tail of

epididymis

Scrotal

cavity

Tunica

albuginea

Testis

Seminiferous

tubule

Rete testis

Head of

epididymis

Spermatic cord

Efferent

ductules

Epithelium

of

epididymis

Stereocilia

Flagella of

spermatozoa

in lumen of

epididymis

Accessory Glands

The seminal vesicles, prostate gland, and

bulbourethral

glands give semen a mixture of secretions

Four Functions:

Activate spermatozoa

Provide nutrients spermatozoa need for motility

Propel spermatozoa and fluid along reproductive trace

Produce buffers that counteract acidity of the urethral and vaginal environments

Accessory Glands

(a)

Ureter

Ductus deferens

Seminal vesicle

Ampulla of

ductus deferens

Prostate gland

Urethra

Bulbourethral

gland

Ejaculatory duct

Duct of

seminal vesicle

Urinary

bladder

Urogenital

diaphragm

Prostatitis

is the inflammation of the prostate caused by a bacterial infection.

Symptoms are pain in lower back,

p

erineum, and painful urination

Semen

Typical ejaculation releases 2-5ml of semen

Volume of fluid produced by an ejaculation, called an

ejaculate

, contains:

Spermatozoa: 20-100 million per ml of semen

Seminal Fluid

Enzymes

External Genitalia

Consists of the scrotum and the penis

The penis is a tubular organ that conducts urine to exterior and semen into a female’s vagina during sexual intercourse

Three parts:

Root

: fixed portion that attaches penis to body wall

Body

(shaft): tubular, movable portion

Glans

: expanded distal end that surrounds external/ urethral orifice

Penis

Most of body consists of three cylindrical columns of

erectile tissue

When smooth muscle relaxes, blood flow increases and the vascular channels engorge with blood. This causes an

erection

.

Testosterone

Five functions:

Stimulates spermatogenesis and promotes functional maturation of spermatozoa

Affects CNS function, including libido(sexual drive) and related behaviors

Stimulate metabolism throughout the body

Establishing and maintaining male secondary sex characteristics (facial hair, increased muscle mass and body size)

Maintaining accessory glands and organs of the reproductive tract

The Reproductive System of the Female

Objectives:

Describe the components of the female reproductive system

Outline the processes of meiosis and oogenesis in the ovaries

Identify the phases and events of the ovarian and uterine cycles

Describe the structure, histology, and functions of the vagina

Summarize the anatomical, physiological, and hormonal aspects of the female reproductive cycle

Woman’s Reproductive System

Produces sex hormones and functional gametes

Protects and supports a developing embryo and nourishes a newborn infant

Principle organs are the ovaries, uterine tubes, uterus, and vagina

Woman’s Reproductive System

Uterine tube

Broad ligament

Ovary

Vesicouterine pouch

Urinary bladder

Pubic symphysis

Urethra

Greater vestibular gland

Clitoris

Labium minus

Labium majus

Anus

Vagina

Cervix

Fornix

Sigmoid colon

Rectouterine

pouch

Endometrium

Perimetrium

Uterus

Myometrium

Paraurethral

glands

Rectum

The Ovaries

Three main functions:

Production of immature gametes, or

oocytes

Secretion of female sex hormones (estrogen)

Secretion of

inhibin

, involved in the feedback control of pituitary FSH production)

A typical ovary is 5cm long, 2.5cm wide, and 8mm thick

The Ovaries

(b)

(a)

Uterine

tube

Mesovarium

Medulla

Corpus

luteum

Cortex

Tunica

albuginea

Mature

follicle

Egg nest

Ovarian

hilum

Broad

ligament

Uterus

Ovarian

ligament

Uterine tube

Fimbriae

Ovarian artery

and vein

Suspensory

ligament

Infundibulum

Ureter

Uterosacral ligament

Vaginal wall

Cervix

Cervical os

Vaginal rugae

Ovary

Broad

ligament

Broad

ligament

Suspensory

ligament

Mesovarium

Retractor

Oogenesis

Oogensis

, or ovum production, begins before a woman’s birth, accelerates at puberty, and ends at

menopause

Occurs on a monthly basis as part of the

ovarian cycle

Development of oogonia, or female stem cells, stop undergoing meiosis before birth

Does not turn into an ovum until puberty

Oogenesis

Tetrad

OOGENESIS

Primary

oocyte

(may not

occur)

Secondpolarbody

Secondary oocyte (haploid)

If fertilization occurs after ovulation, MEIOSIS II is completed

Secondary oocyteovulated in metaphaseof MEIOSIS II

Ovum(haploid)

Primary oocyte (diploid)

MEIOSIS I completed after puberty

Synapsis and tetrad formation

DNA replication (before birth)

MITOSIS ofoogonium(before birth)

Maturation of gamete

MEIOSIS II begun in the tertiary follicle and completed only if fertilization occurs

First polar

body

The Ovarian Cycle

The

Ovarian Cycle

is the monthly chain of events that leads to ovulation

It is divided into two phases:

Follicular phase

Luteal phase

Ovarian follicles are specialized structures in the cortex of ovaries where both oocyte growth and meiosis 1 occur

The Ovarian Cycle

It involves six steps:

Formation of primary follicles

Formation of secondary follicles

Formation of tertiary follicles

Ovulation

: the tertiary follicle releases the secondary oocyte and is transferred to the uterine tube

Formation & degeneration of the

Corpus

Luteum

(endocrine structure formed to prepare uterus for pregnancy)

Unless fertilization occurs, the Corpus

Luteum

begins to degenerate

The Ovarian Cycle

STEP

STEP

STEP

Tertiary

follicle

Primary

oocyte

Follicle

cells

Ovary

Thecal

cells

Zona

pellucida

Primordial follicles

in egg nest

Granulosa

cells

Primary

oocytes

Primary oocyte

Antrum

containing

follicular

fluid

Granulosa

cells

Primary

follicles

Secondary

follicle

Granulosa

cells

Nucleus of

primary

oocyte

Zona

pellucida

Thecal

cells

1

2

3

STEP

STEP

STEP

Corpus albicans

Released

secondary oocyte

Secondary

oocyte within

corona radiata

Follicular

fluid

Ruptured

follicle wall

Outer

surface

of ovary

Ruptured tertiary follicle

Corona radiata

Ovulation

Corpus luteum

4

5

6

The Uterine Tubes

The

uterine tubes

are hollow muscular tubes

Peristaltic contractions move ovum towards uterus

It takes 3-4 days for ovum to travel to uterus

It provides nutrients to the sperm and developing pre-embryo

The Uterus

The

uterus

provides mechanical protection, nutritional support, and waste removal for developing embryo

Contractions in muscular wall help eject the fetus at birth

The Uterus

(a)

Uterus

Isthmus

Ampulla

Infundibulum

Fimbriae

Posterior view

The Uterine Cycle

The

uterine cycle

is a repeating series of changes in the structure of the inner layer of the uterus (28 days in length)

The Uterine Cycle

Three phases:

Menses

Menses: interval marked by the degeneration of the inner layer of the uterus

Menstruation: process of losing 35-50ml of blood

The Proliferative Phase

Epithelial cells multiply and restore the uterus epithelium

The

Secretory

Phase

Glands enlarge, accelerating rate of secretion

Menarch and Menopause

Menarch

is the first cycle at puberty, normally at age 12

Menopause

is the termination of the uterine cycle, normally between the ages of 45-55

The Vagina

The

vagina

is an elastic, muscular tube extending between the cervix and the

vestibule

, bounded by external genitalia

The

vaginal canal

is the proximal end where the cervix project into

The Vagina

Three Functions:

Passageway for the elimination of menstrual fluids

Receive the penis during sexual intercourse, and holds sperm prior to passage into the uterus

Forms inferior portion of

birth canal

Anatomy & Histology of the Vagina

Lined by nonkeratinized stratified squamos epithelium (when relaxed, folds form rugae)

Lining is moistened by secretions

Contains a population of resident bacteria

Metabolic activity creates an acidic environment

Vaginitis

is an inflammation of the vaginal canal caused by fungi, bacteria, or parasites

Causes discomfort and reduced fertility

The External Genitalia

The

vulva

is the area containing the female external genitalia

Vagina opens into the vestibule

The

clitoris

is a small rounded projection that engorges with blood during sexual intercourse

The External Genitalia

Anus

Labia

majora

Labia

minora

Glans of

clitoris

Mons pubis

Prepuce

of clitoris

Urethral

opening

Vestibule

Vaginal

entrance

Hymen (torn)

The Mammary Glands

Mammary glands

, in a woman’s breast, produce milk to feed their newborn infant

Each breast has a

nipple

, where the underlying mammary gland opens to the body surface

Mammary Glands

(a)

Pectoralis

major muscle

Pectoral fat pad

Suspensory

ligaments

Lactiferous

duct

Areola

Nipple

Lactiferous

sinus

Lobes of the

mammary gland

Hormones

Circulating hormones control the

female reproductive cycle

, coordinating the ovarian and uterine cycles

Estrogen

Estrogen has five main functions:

Stimulating bone and muscle growth

Maintaining female sex characteristics

Affecting CNS activity

Maintaining functional accessory reproductive glands and organs

Stimulating the repair and growth of the inner layer of the uterus

The Physiology of Sexual Intercourse

Objective:

Discuss the physiology of sexual intercourse as it affects the reproductive systems of males and females

Male Sexual Function

During sexual

arousal

, erotic thoughts, stimulation of sensory nerves in genital region, lead to an erection of the penis

Ejaculation

is the ejection of semen from the penis as the result of muscular contraction along the sides of the penis

Associated with intensely pleasurable sensation known as orgasm

Impotence

is the inability to achieve or maintain an erection

Female Sexual Function

During sexual arousal, engorgement of erectile tissue of clitoris

Orgasm is found by stimulation of touch sensations

Contractions of uterine and vaginal wall gives rise to pleasurable sensations

Sexual Transmitted Disease

STD

’s are transferred primarily during sexual intercourse

Chlamydia

can cause

pelvic inflammatory disease

as well as

infertility

Jobs in the Reproductive Field

Gynecologist

-study

and treat problems with the female genital, rectal and urinary

organs

Fertilization Researcher

-

studies the effects of in-vitro fertilization, stem cell biology, animal assisted reproductive methods and the effects of different toxins on a

fetus

Urologist

-A physician who specializes

in

diseases of the urinary organs in females and the urinary and sex organs in males.

Aging and the Reproductive System

Objective:

Describe the changes in the reproductive system that occur with aging

Menopause

Menopause

is the time the ovulation and menstruation cease

Premature menopause is a depletion of follicles before age 40

Is accompanied by a decline of estrogen which leads to reductions of uterus and breasts; even linked to osteoporosis

The Male Climacteric

Male Climacteric is the period of declining reproductive function

Circulating testosterone decreases between ages 50-60

Sperm production continues, but reduction in sexual activity

Integration with Other Systems

For proper function, reproductive, digestive, endocrine, nervous, cardiovascular, and urinary systems must all function normally

Clinical Patterns

Reproductive Disorders

Tumors, such as testicular, prostate, ovarian, or uterine cancers

Inflammation and infection, such as

prostatitis

, PED, toxic shock syndrome, and STD’s

Uterine disorders such as endometriosis

Trauma, such as testicular torsion and inguinal hernias

Congenital disorders, such as

crytorchidism

Finished!!!